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Molecular structure of dirhenium decacarbonyl
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Elwrier
Sequoia
Printed
in The
SA..
Chemisfr.v
319
Lau~ann~
Netherlands
MOLECULAR
STRUCTURE
N. I. GAPOTCHENKO, A. A. JOHANSSON
OF DIRHENIUM
N. V. ALEKSEEV.
DECACARBONYL
N. E. KOLOBOVA.
K. N. ANISIMOV,
I. A. RONOVA
AND
Ittstitrtre
of Organo-Eientettr
(Received
August
Cot?tpouttris,
Acudetny
of Sciences
of rhe U.S.S.R.,
Moscow
(U.S.S.R.)
4th, 1971)
SUMhlARY
The molecular structure of Re,(CO)lo has been determined by electron diffraction methods and the following bond lengths found: Re-Re 3.04, Re-C 2.01 and C-O 1.16 A. Equatorial CO groups of neighbouring rhenium atoms are found to be in an eclipsed conformation. Only dimanganese decacarbonyl has been studied in detail’ -’ of the series of binuclear carbonyls of the Group VII metals of the type M1(CO)lo. A complete X-ray investigation has been undertaken5 for TcJCO)~~, but for the Re,(CO),, molecule only the Re-Re bond length has been established’. Because the metal-metal bond energies in Mn2(C0)10 and Re2(CO)10 differ considerably (0.96 and 2.22 eV respectively), it seemed desirable to determine the complete structure of dirhenium decacarbonyl. Dirhenium decacarbonyl has been prepared by the reaction of KReO, with carbon monoxide at 270 atm and 270” in an autoclave fitted with a copper piston. The product was purified by repeated crystallization from benzene followed by sublimation in wzcuo.
Electron diffraction patterns were recorded using an EG-100M electronograph with an r3-sector. The nozzle-to-plate distances were ca. 400 and 200 mm, and an accelerating potential of 40 kV was used. The modified molecular intensity function sM(s), calculated in the usual way’, covers the s range from 1.3 to 27.6 A-‘. A choice of a preliminary model was made on the basis of an analysis of the radial distribution function. It was assumed that the Re2(CO),, molecule is approximately isostructural with that of Mn,(CO),,, and has Dkl symmetry. In addition, the possibility of rotation of the Re(CO), groups about the Re-Re bond leading to ‘D, symmetry was also taken into account. The structure was refined by a leastsquares procedure using a version of the stage-by-stage parameter refinement applied to the molecular intensity function *. To achieve this refinement, non-nuclear scattering was taken into account in the program for the calculation of the theoretical SM (s) curves. Hartree-Fock potentials lo for the C and 0 atoms and Thomas-FermiDirac potentiaIs” for the Re atom were used. The fiual value of discrepancy index is R
=J x C~M(s),,,--k.sM(s),,,,,l~ = c L-sw4explz
J. Organometul. Chem,35 (1972)
11
so/
-
0
320
N. I. GAPOTCHENKO
et at_
RESULTS AND DISCUSSION
The molecular geometry of Re,(CO)r,-, is presented in Fig. 1. The data obtained show that the molecule consists of two Re(CO)s fragments with a Re-Re bond length of 3.04 pi (in crystals 3.02 A)‘. In contrast to the analogous manganese and technetium carbonyls the equatorial carbonyl groups in Re,(CO)10 are in an eclipsed configuration @ah symmetry).
The Re atom exists in a slightly distorted octahedral configuration with the C =rar-Re-Cequatortir angle equal to 88”. The mean Re-C bond length of 2.01 A is the same for the axial and equatorial positions. The mean C-O distance is 1.16 A. REFERENCES
1 L. F. DAHL ANDR. E. RUNDLE, Acra CrysraUogr., 16 (1963) 419. 2 L. F. DAHL, E. I~HIWIANDR. E. RUNDLE, J. Chem. Phys., 26 (1957) 1750. 3 N. I. GAPOTCHENKO, N. V. ALEKXW, K. N. ANISIMOV, N. E. KOL~BOVA AND I. A. RONOVA,2%. Stmkt. Khim., 9 (1968) 392. 4 A. ALMENNINGEN,G. G. JACOESENAND H. M. SEIP, Actu Chem. Scund., 23 (1969) 865. 5 M. F. BAILEYAND L. F. DAHL, Inorg. Chem., 4 (1965) 1140. 6 H. J. S~EC ANDG. JUNK, J. Amer. Chem. Sot., 89 (1967) 2836. 7 E. N. VEDEN~V, Programme of computing treatment of results of electronographic investigations. Complex EKRAFO??- Computing Centre of MOSCOWState University, Moscow, 1969. 8 N. I. GAPOTCHENKO AND N. V. ALEKSEW, Zh. St&t. Khim., 12 (1971) 530. 9 N. I. GA POTIXZNKO, N. V. ALEKSEEXAND I. A. RONOVA, Zh. Strdct. Khim., 11 (1970) 131. 10 T. G. STRAND AND R. A. BONHAM, J. Chem. Phys., 40 (1964) 1676. 11 R. A. Bo.WD T. G. STRAW, J. Chem. Phys., 39 (1963) 2200. J. Organontetal. Chem., 35 (1972)
uf Oryanomrrullic
Elwrier
Sequoia
Printed
in The
SA..
Chemisfr.v
319
Lau~ann~
Netherlands
MOLECULAR
STRUCTURE
N. I. GAPOTCHENKO, A. A. JOHANSSON
OF DIRHENIUM
N. V. ALEKSEEV.
DECACARBONYL
N. E. KOLOBOVA.
K. N. ANISIMOV,
I. A. RONOVA
AND
Ittstitrtre
of Organo-Eientettr
(Received
August
Cot?tpouttris,
Acudetny
of Sciences
of rhe U.S.S.R.,
Moscow
(U.S.S.R.)
4th, 1971)
SUMhlARY
The molecular structure of Re,(CO)lo has been determined by electron diffraction methods and the following bond lengths found: Re-Re 3.04, Re-C 2.01 and C-O 1.16 A. Equatorial CO groups of neighbouring rhenium atoms are found to be in an eclipsed conformation. Only dimanganese decacarbonyl has been studied in detail’ -’ of the series of binuclear carbonyls of the Group VII metals of the type M1(CO)lo. A complete X-ray investigation has been undertaken5 for TcJCO)~~, but for the Re,(CO),, molecule only the Re-Re bond length has been established’. Because the metal-metal bond energies in Mn2(C0)10 and Re2(CO)10 differ considerably (0.96 and 2.22 eV respectively), it seemed desirable to determine the complete structure of dirhenium decacarbonyl. Dirhenium decacarbonyl has been prepared by the reaction of KReO, with carbon monoxide at 270 atm and 270” in an autoclave fitted with a copper piston. The product was purified by repeated crystallization from benzene followed by sublimation in wzcuo.
Electron diffraction patterns were recorded using an EG-100M electronograph with an r3-sector. The nozzle-to-plate distances were ca. 400 and 200 mm, and an accelerating potential of 40 kV was used. The modified molecular intensity function sM(s), calculated in the usual way’, covers the s range from 1.3 to 27.6 A-‘. A choice of a preliminary model was made on the basis of an analysis of the radial distribution function. It was assumed that the Re2(CO),, molecule is approximately isostructural with that of Mn,(CO),,, and has Dkl symmetry. In addition, the possibility of rotation of the Re(CO), groups about the Re-Re bond leading to ‘D, symmetry was also taken into account. The structure was refined by a leastsquares procedure using a version of the stage-by-stage parameter refinement applied to the molecular intensity function *. To achieve this refinement, non-nuclear scattering was taken into account in the program for the calculation of the theoretical SM (s) curves. Hartree-Fock potentials lo for the C and 0 atoms and Thomas-FermiDirac potentiaIs” for the Re atom were used. The fiual value of discrepancy index is R
=J x C~M(s),,,--k.sM(s),,,,,l~ = c L-sw4explz
J. Organometul. Chem,35 (1972)
11
so/
-
0
320
N. I. GAPOTCHENKO
et at_
RESULTS AND DISCUSSION
The molecular geometry of Re,(CO)r,-, is presented in Fig. 1. The data obtained show that the molecule consists of two Re(CO)s fragments with a Re-Re bond length of 3.04 pi (in crystals 3.02 A)‘. In contrast to the analogous manganese and technetium carbonyls the equatorial carbonyl groups in Re,(CO)10 are in an eclipsed configuration @ah symmetry).
The Re atom exists in a slightly distorted octahedral configuration with the C =rar-Re-Cequatortir angle equal to 88”. The mean Re-C bond length of 2.01 A is the same for the axial and equatorial positions. The mean C-O distance is 1.16 A. REFERENCES
1 L. F. DAHL ANDR. E. RUNDLE, Acra CrysraUogr., 16 (1963) 419. 2 L. F. DAHL, E. I~HIWIANDR. E. RUNDLE, J. Chem. Phys., 26 (1957) 1750. 3 N. I. GAPOTCHENKO, N. V. ALEKXW, K. N. ANISIMOV, N. E. KOL~BOVA AND I. A. RONOVA,2%. Stmkt. Khim., 9 (1968) 392. 4 A. ALMENNINGEN,G. G. JACOESENAND H. M. SEIP, Actu Chem. Scund., 23 (1969) 865. 5 M. F. BAILEYAND L. F. DAHL, Inorg. Chem., 4 (1965) 1140. 6 H. J. S~EC ANDG. JUNK, J. Amer. Chem. Sot., 89 (1967) 2836. 7 E. N. VEDEN~V, Programme of computing treatment of results of electronographic investigations. Complex EKRAFO??- Computing Centre of MOSCOWState University, Moscow, 1969. 8 N. I. GAPOTCHENKO AND N. V. ALEKSEW, Zh. St&t. Khim., 12 (1971) 530. 9 N. I. GA POTIXZNKO, N. V. ALEKSEEXAND I. A. RONOVA, Zh. Strdct. Khim., 11 (1970) 131. 10 T. G. STRAND AND R. A. BONHAM, J. Chem. Phys., 40 (1964) 1676. 11 R. A. Bo.WD T. G. STRAW, J. Chem. Phys., 39 (1963) 2200. J. Organontetal. Chem., 35 (1972)